In the past there have been known navigation devices and navigation systems wherein a user is guided by using map data and road data to conduct a search for a route from a desired point of departure to a destination.
Examples of such navigation devices and navigation systems put into practice include automobile-mounted car navigation devices for guiding an operator along a route.
The aforementioned car navigation systems use a GPS (global positioning system), wherein GPS signals sent from a plurality of GPS satellites orbiting the globe are received by a GPS antenna; the satellite positions, time information, and the like included in the GPS signals are analyzed; and the position is specified. The number of the GPS satellites must be at least four. The independent positioning accuracy of a GPS is generally within 10 m, but this can be improved to 5 m or less by using a DIPS (differential GPS).
Recently, the performance of portable phones, PHs, and other portable communication terminal devices has been dramatically improving, and these devices have become more multifunctional. Data communication functions in particular have been strengthened in addition to voice communication functions, and users are provided with various data communication services via the Internet. There has particularly been a trend according to which positioning units that have until now been installed only in some portable phones, e.g., GPS receivers and other devices which determine position by receiving signals from GPS satellites, are currently being installed in all models of portable phones known as third-generation phones.
Navigation systems for automobiles (car navigation systems) are being developed as an applied technology, and also being put into practice are communicable navigation systems for pedestrians, wherein a route search request is sent to a route search server by using a portable phone as a navigation terminal, and map/route guidance distributed from the route search server is received as a result.
Furthermore, a pedestrian navigation system is a system in which not only portable phones, but also headphone stereos and other music players, portable compact game devices, PDAs, and other portably terminals can be used as navigation terminals. A route guidance function including public transportation is preferably added, and the route search server stores public transportation routes and service schedule data as traffic network data in addition to road network data for pedestrian route searches.
This type of pedestrian navigation system generally provides guidance by searching for a route from the point of departure to the destination using airplane, train, electric train, bus, or other transportation means on the basis of the departure time, the point of departure, the destination, the arrival time, and other route search conditions.
Specifically, a pedestrian navigation system refers to traffic network data, which is a database of public transportation route data and service schedule data, and suggests one or more candidates for guidance routes (trains and other transportation means) which join the point of departure with the destination, including connections, and for which usable transportation means are reached sequentially as part of the route to satisfy the route search conditions. It is common to enable the time required, the number of connections, the fares, and other conditions to also be specified as route search conditions.
From this manner of background art, Patent Document 1 (Japanese Laid-open Patent Application No. 2003-186392) given below, for example, discloses as a “map display” a technique whereby the display screen is split in the map display of the navigation system, and a detailed map and its display scope are displayed in a frame or the like in a wide-area map by a method for superposing a wide-area map over another map.
The aforementioned Patent Document 1 discloses a technique whereby the display screen is split when the scrolling operation is performed, the map being scrolled is displayed on one of the split screens, the wide-area map is displayed on the other split screen, and the area being scrolled is displayed in the wide-area map. This makes it possible to easily understand what area is being represented by the map displayed on the display screen when the map is scrolled.